Oct 29 (Reuters) - A privately owned prototype space planeaced its debut test flight in California but was damaged afterlanding when a wheel did not drop down, developer Sierra NevadaCorp said on Tuesday.

The Dream Chaser is one of three space taxis underdevelopment in partnership with NASA to fly astronauts to theInternational Space Station following the retirement of thespace shuttles in 2011.

While competitors Space Exploration Technologies - aprivately owned firm also known as SpaceX - and Boeing are working on seven-person capsules that return to Earth viaparachutes, Sierra Nevada's Dream Chaser resembles a miniaturespace shuttle with wings to glide down for a runway landing.

The company took a significant step toward proving DreamChaser can fly with its first unmanned glide test at Edwards AirForce Base in Mojave, California, on Saturday, Sierra NevadaVice President Mark Sirangelo told reporters on a conferencecall.

A full-size Dream Chaser model was carried to an altitude ofabout 12,500 feet (3,810 meters) by a heavy-lift helicopter andreleased for a minute-long glide back to the runway.

"The first thing we needed to do was find out 'Does thisshape, does this type of vehicle actually fly? Is itair-worthy?' Although all the computer modeling and thesimulations told us it was, there had not been a lifting body ofthis type flown since the 1970s," Sirangelo said, referring tothe test flight of NASA's prototype space shuttle Enterprise.

After being released, the autonomously controlled DreamChaser successfully positioned itself for flight, flared itsnose to slow for touchdown and settled on the runway, Sirangelosaid.

However, one of the vehicle's three landing gears did notdeploy, causing the plane to skid off the landing strip and endup in the sand, he said.

Engineers are still assessing how much damage was sustained.Sirangelo said the crew cabin and onboard computers were notdamaged.

The landing gear used during the test flight is not the sameequipment planned for the orbital vehicles, he added.

Ironically, the accident may speed up Sierra Nevada'splanned piloted test flight next year. The vehicle had beenscheduled for a second autonomous flight in California beforebeing returned to its Colorado manufacturing facility to beoutfitted for a piloted flight.

"We were fortunate enough to get almost all the data weneeded on the very first flight. If that's the case, we may justmove on to the next phase of the program," Sirangelo said.

NASA hopes to buy rides commercially to carry its astronautsto the space station by 2017.